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Metabones Speed Booster ULTRA 0.71x M43

Metabones and Caldwell Photographic have launched a new Speed Booster ULTRA series of "focal lens reducing" adapters designed for Micro Four Thirds cameras. Like the original Metabones Speed Booster announced in January 2013, the Speed Booster ULTRA m43 has a magnification of 0.71x, and so it effectively reduces the crop factor of mirrorless Micro Four Thirds mount cameras from 2.0x to 1.4x, and is almost perfectly corrected for use with all 35mm full-frame SLR lenses. The Speed Booster ULTRA for Micro Four Thirds is available for $649 (Canon EF mount) and $479 (Nikon F mount) plus shipping and applicable taxes and duties).

Metabones Press Release

Metabones Speed Booster ULTRA 0.71x M43 with Autofocus

Caldwell Photographic Inc. and Metabones® are pleased to announce a new Speed Booster ULTRA series of focal reducing adapters designed for Micro Four Thirds mirrorless cameras. Like the ULTRA series for Sony E-mount, the new Speed Booster ULTRA m43 uses an advanced 5-element 4-group optical design incorporating ultra-high index tantalum-based optical glass. However, the new design is specifically optimized for the Micro Four Thirds sensor and filter stack, and as a result achieves an astonishing level of performance that sets a new standard for focal reducers.

Like the revolutionary original Metabones Speed Booster® announced in January 2013, the Speed Booster ULTRA m43 has a magnification of 0.71x, and so it effectively reduces the crop factor of mirrorless Micro Four Thirds mount cameras from 2.0x to 1.4x. However, the new ULTRA design makes very effective use of exotic materials at the furthest limit of glassmaking technology, and as a result is almost perfectly corrected for use with all fullframe SLR lenses regardless of aperture. The Speed Booster ULTRA m43 will also work extremely well with many DX and APS-C format lenses provided the image circle of the lens is large enough. Optical performance of the new Speed Boosters is so good that the MTF of any lens attached to it will be improved. Even the latest generation of ultra-high performance SLR lenses such as the Zeiss Otus series can be improved by adding a Speed Booster ULTRA m43.

At the maximum aperture of f/0.90 (i.e., with an f/1.2 master lens) the sharpness and contrast are extraordinary across the entire image circle. At just one-third stop down to f/1.0 the performance is equal to or better than the best photographic lenses used at their optimum apertures. An additional stop down to f/2.0 yields performance that is rarely encountered in photographic optics. In practice, what all of this means is that the new Speed Boosters will always enhance and never degrade the performance of the attached master lens.

And other aspects of optical performance haven’t been sacrificed in order to obtain high MTF, either. Figure 5 shows that there is less than 1 stop of corner illumination falloff even wide-open at f/0.9. There is no vignetting at all after the output aperture reaches f/2.82. Figure 6 shows that rectilinear distortion added by the Speed Booster ULTRA m43 is negligible at less than 0.7%. The charts shown in Figures 2 through 6 below show the optical performance of the Speed Booster ULTRA m43 when mounted behind an ideal “perfect” lens.

Like all Metabones Speed Boosters, the Speed Booster ULTRA m43 is optimized to correctly account for the camera’s filter stack located near the sensor surface3. This is especially critical at the extremely large apertures made possible by Speed Booster technology. As a result of this careful optimization, an enormous range of full-frame optics, ranging from vintage film lenses to the latest digital designs, will function flawlessly when adapted to Micro Four Thirds camera bodies.

The Speed Booster ULTRA for Micro Four Thirds will be available starting in July 2015 from the Metabones website and its worldwide dealer network for US $649 (Canon EF mount) and US $479 (Nikon F/G mount), plus shipping and applicable taxes and duties. Additional lens mounts are being developed and will be released in the near future.

Autofocus with an Optimum Balance of Accuracy, Speed, Consistency and Reliability

New in Speed Booster ULTRA for Canon EF Mount to Micro Four Thirds is autofocus on Panasonic camera bodies, subject to certain limitations (see specifications for details). We are pleased to report that Panasonic Micro Four Thirds camera bodies are capable of autofocusing accurately even if the maximum aperture of the Speed Booster and the lens combined is in the sub-f/1.0 range. Although our first and foremost priority is accuracy, we are able to make great strides in autofocus speed as well, which is significantly faster than a DSLR Four Thirds lens on a Panasonic Micro Four Thirds camera (with adapter), or our E-mount offerings on Sony cameras prior to Alpha 7R II. For existing Metabones patrons with any previously released Canon EF to Micro Four Thirds mount Speed Boosters and Smart Adapters, a firmware update (Windows/Mac) to add autofocus is available for download on Metabones' web site.

Measured MTF Using a 55mm Zeiss Otus as the Master Lens:

The MTF curve in Figure 3 indicates that the Speed Booster ULTRA m43 has truly phenomenal performance at f/1.0, which is the output aperture you will get when the master lens is set to f/1.4. Extremely low levels of aberration in the Speed Booster ULTRA m43 combined with the aberration-reducing tendency inherent in focal reducers means that even extremely high performing lenses such as the renowned Zeiss Otus series can actually be improved! This is illustrated in the pair of measured MTF graphs below in Figure 7.

The 55mm f/1.4 Zeiss Otus is widely recognized as perhaps the finest large aperture photographic lens ever produced, and yet the Speed Booster ULTRA m43 transforms it into a 39mm f/1.0 lens with even higher MTF. In fact, the resulting combination is likely the highest-performing f/1.0-class photographic lens available to the public.

Lens Mounts: Canon EF and Nikon F/G at release; other mounts to follow in the near future

Lens Compatibility: Any full-frame (36 mm x 24 mm format) SLR lens with the appropriate mount can be used. DX format lenses can be mounted but may result in vignetting when the full Micro Four Thirds format is used, depending on the lens. DX lenses are fully supported when used on the Panasonic GH4 in Cinema 4k mode, and will function without abnormal vignetting. Canon EF-S lenses are not supported, but third-party EF-mount APS-C lenses can be mounted and will have full electronic functionality.

Autofocus supported for Canon EF version subject to the following known limitations:

Contrast-detect autofocus support on Panasonic cameras only.
AFC (continuous AF) and AFF (flexible AF) modes are not supported.
Video AF may hunt more than a native lens.
Autofocus is not supported with previous generation Tamron VC lenses and Contax N lenses modified to EF mount by Conurus Canada. (Newer Tamron lenses such as the 24-70/2.8 VC A007 and 70-200/2.8 VC A009 work fine.)
Switching from manual focus or full-time manual focus (FTM) to autofocus may occasionally result in focus failing to lock or inaccurate focus. Activating autofocus for a second time will resolve this issue.
AF accuracy is lens-dependent.